Pipe Fragment
Click on the title above each image to see the animated model of the fracture surface
created with Helicon Focus and Helicon 3D Viewer.
Right-click on each image below and select View Image to see it at full resolution in a new browser window.

First Try - 20X magnification
Stack: 0
.005 inch increments.
Fracture at 20X magnification
Higher Magnification: 50X.
Stack: 0.003 inch increments.
Fracture at 50X magnification
Another Place - 40X magnification.
Stack: 0.004 inch increments.

Fracture at 40X magnification
This is one of a great many fragments of a gas pipe that failed on a cold Winter day.  It had about the worst combination of brittleness, poor welding, and exposure to diurnally varying thermal stresses that I have ever seen.  Exposure to hydrogen generated by corrosion of fresh steel fracture surfaces by the mercaptans (used as an odorant) caused the formation of intergranular cracks as seen here and in cross sections of other pieces of the pipe.

Without Helicon Focus and Helicon 3D Viewer, these fracure surfaces would be too rough to photograph with the light microscope.